Refreshed Grand Cherokee Powertrains: Greener or Faster

Chrysler Group LLC's heavily revised powertrain options for the 2014 Jeep Grand Cherokee SUV include a first-time diesel, new eight-speed transmission and updates to existing 3.6-liter V-6 and 5.7-liter V-8 engines.

The diesel a first for the segment in American market also will be available in the 2014 Ram 1500 pickup truck. Chrysler notes that the 240-hp engine's 420 lb-ft of torque handily exceeds the 390 lb-ft delivered by the Grand Cherokee's optional 5.7-liter V-8.

The eight-speed automatic transmission, also being introduced in the new Ram, replaces the five- and six-speed automatics used previously with the V-6 and V-8, respectively. Chrysler says the new gearbox boosts highway fuel economy by 2 mpg and raises the trailer towing capacity of the V-6-powered Grand Cherokee by 1,200 lbs to 6,200 lbs.

The diesel, paired with the new 8-speed automatic, can deliver 30 mph on the highway in two-wheel-drive mode, according to the company.

For buyers who favor on-road performance, the SRT version of the Grand Cherokee benefits from a change to the new 8-speed transmission. The model uses the carryover 6.4-liter Hemi V-8 with cylinder deactivation to make 470 hp and 465 lb-ft of torque.

The revised powertrain gives the 2014 SRT increases towing capacity to 7,200 lbs from 5,000 lbs for the previous model.

The powertrain also enables the SRT to scoot from zero to 60 mph in 4.8 seconds and achieve a claimed top speed of 160 mph. An electronic launch control system maximizes acceleration and directs 70% of engine power to the rear wheels for what Chrysler describes as a "more pronounced rear-wheel-drive experience." Six-piston Brembo brakes enable the SRT to stop from 60 mph in an impressively short 116 feet.